Behavioral studies of the covariance between alcohol self-administration patterns and phases of the menstrual cycle in female rhesus monkeys are proposed. Established techniques for operant control of intravenous alcohol self-administration will be used. Monkeys will be observed over 12 to 24 consecutive menstrual cycles. Alcohol self-administration patterns during natural menstrual cycles will be compared with cycles during which hormones are artificially stabilized with estrogens, in order to identify the possible contribution of reproductive hormone cycles to alcohol use patterns. Menstrual cycle phases will be determined by vaginal smears, observation of menstrual bleeding and frequent monitoring of estradiol, FSH and LH. The acute and chronic effects of alcohol on pituitary-gonadal hormones essential for normal female reproductive function will be studied. Episodic secretory patterns of estradiol, LH and FSH will be determined by radioimmunoassay of integrated plasma samples. Profiles of these hormones will be determined at 3 menstrual cycle phases: menstruation, ovulation and the premenstruum. Repeated neuroendocrine measures will be taken in the same female at 3 to 6 month intervals over 1 to 2 years to assess possible cumulative effects of chronic alcohol use. If chronic alcohol use changes neuroendocrine homeostasis or menstrual cycle regularity, the extent and rate of recovery of function during alcohol abstinence will be studied. The proposed bio-behavioral studies should clarify possible hormonal determinants of alcohol self-administration in females and indicate if alcohol has direct toxic effects on the episodic secretory patterns of hormones which regulate normal female reproductive function.